Send multiple bytes to server device

I was plan to send 4 bytes to peripheral device (base on app simpleBLEperipheral), which include the time value, I modify the simpleGATTprofile to add a 4 byte attr named clock, I can read the vlaue through BTOOL, but can not write total 4 bytes, through the handle peripheral returned, I can only write the first byte, other wise system will return INVALID_SIZE, which part of the simpleGATTprofile should I change to fix this problem?